Rotary regenerative heat exchanger

ABSTRACT

A rotary regenerative heat exchanger including a device for detecting the rate of flow of leakage of heat exchange fluid between a seal and the relevant surface of the matrix and for controlling the application of pressurizing fluid to a pressurized seal in response to the detected rate of leakage flow, thereby to control the rate of leakage flow of heat exchange fluid and to maintain it at a desired value.

United States Patent Penny Apr. 29, 1975 l5 l ROTARY REGENERATWE HEAT3.039265 6/l962 Williamsct al. 165/7 x EXCHANGER 3.232.335 2/1966Kalhfleisch 165/9 [76] Inventor: Robert Noel Penny, l1 Alderbrooksolihunawarwickshire Prmrury E.\'mnmerAlbert W. Davis, Jr. EnglandAllurney, Agent. or Firm-Hanke, Gifford, Patalidis & Dumorit 22] Filed:Dec. 7. 1972 [-1] Appl. No. 3l3,l74 [57] ABSTRACT A rotarv regenerativeheat exchanger including a de- 30 F A l t P l I U pp i Data g were fordetecting the rate of flow of leakage of heat l Umml 890ml exchangefluid between a seal and the relevant surface of the matrix and forcontrolling the application of 2? 3 63 pressurizing fluid to apressurized seal in response to g 'l 2 9 the detected rate of leakageflow, thereby to control l 0 l the rate of leakage flow of heat exchangefluid and to Referenceg Cited maintain it at a desired value.

UNITED STATES PATENTS 4 Claims, 3 Drawing Figures 2.747.843 5/1956 Coxct all. 165/7 X II II n 1 I 5 1 a ll lb 7 l i l2 "g 3 4 IO 1} 4 l7 l9 sROTARY REGENERATIVE HEAT EXCHANGER BACKGROUND OF THE INVENTION l. Fieldof the Invention The invention relates to a rotary regenerative heatexchanger having a matrix in which flow paths therethrough for thefluids between which heat exchange is to be effected are defined byseals of the kind to which a pressurizing fluid is applied to controlthe loading of the seal on the relevant surface of the matrix. Suchseals are usually in the form of bellows.

I. Prior Art Where the loading of a seal is too great, excessive wear ofthe seal or matrix surface or both will occur. Where the loading of aseal is too small, there will be excessive leakage of heat exchangefluid between the seal and the matrix. The loading of a pressurized sealcan be controlled by adjusting the pressure of pressurizing fluidapplied to the seal to a value at which there is correct runningclearance between the seal and the matrix surface.

SUMMARY OF THE PRESENT INVENTION According to the invention, a rotaryregenerative heat exchanger comprising a matrix, seals defining the flowpaths through the matrix for the fluids between which heat exchange isto be effected and means by which at least one of the seals is arrangedto be subjected to a pressurizing fluid to effect a desired sealloading, includes means for detecting the rate of flow of leakage ofheat exchange fluid between a seal and the relevant surface of thematrix and means for controlling the application of pressurizing fluidto the pressurized seal or seals in response to the detected rate ofleakage flow, thereby to control the rate of leakage flow of heatexchange fluid and to maintain it at a desired value.

Preferably duct means are provided adjacent a seal to lead leakage flowof fluid to a fluid-responsive device arranged to control the supply ofpressurizing fluid applied to the pressurized seal or seals.

The fluid-responsive device may comprise a pressure-actuated spool valveconnected to admit pressurizing fluid to or to exhaust fluid from thepressurized seal or seals. The spool valve may be operated by a pistonor diaphragm responsive to the pressure of leakage fluid.

Alternatively the leakage fluid may be applied to a fluidic switchingdevice arranged to admit pressurizing fluid to or to exhaust fluid fromthe pressurized seal or seals.

In yet another arrangement, the leakage fluid may be applied to apressure transducer arranged to operate electrical means for applyingpressurizing fluid to or to exhaust fluid from the pressurized seal orseals. The electrical means could be a switch controlling an electricmotor or a solenoid arranged to move a fluid control valve.

Whichever means of detecting the rate of leakage flow of heat exchangefluid and controlling the pressure of pressurizing fluid applied to theseal is employed, the control means is adjusted to control the internalfluid pressure in the seal to a value at which there is a predeterminedrate of leakage flow of heat exchange fluid between the seal and theadjacent matrix surface, thereby ensuring that the seal loading ismaintained at its desired value to minimize wear and leakage of fluid.

The pressurized seal or seals may be in the form of pistons ordiaphragms to which the pressurizing fluid is applied. Alternatively thepressurized seal or seals may be in the form of bellows or otherinternally pressurized device to which the pressurizing fluid isapplied.

The pressurizing fluid may be one or other of the fluids between whichheat exchange is to occur or it may be another source of pressurizingfluid.

BRIEF DESCRIPTION OF THE DRAWINGS By way of example, a rotaryregenerative heat exchanger in accordance with the invention is nowdescribed with reference to the accompanying drawings, in which:

FIG. 1 is an axial section through the heat exchanger showing apressure-actuated spool valve for controlling the application of apressurizing fluid to pressurized seals of the heat exchanger,

FIG. 2 is a section on the line II-II in FIG. I, and

FIG. 3 is a fluidic switching device employed in place of the spoolvalve shown in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1and 2, the heat exchanger comprises a disc-like matrix 1 mounted forrotation by a shaft 2 in a housing 3. The matrix I has a plurality ofpores of passages 4 extending parallel with the axis of rotation of thematrix and through which during operation of the heat exchanger thefluids, e.g., compressed air and exhaust gases from a turbine ofa gasturbine engine, are passed in two separated streams defined by seals 5and 6 engaging the ends of the matrix. The seal 5 defines in one end ofthe housing 3 a region 7 to which compressed air from a compressor (notshown) of the gas turbine engine is supplied and a region 8 throughwhich exhaust gases from the turbine (not shown) are exhausted afterpassing through the matrix. The seal 6 defines in the other end of thehousing 3 a region 9, opposite the region 7, through which thecompressed air stream after having been passed through the matrix ispassed to a combustion chamber (not shown) of the engine and a region 10opposite the region 8 through which exhaust gases from the turbine arepassed through the matrix. The seal 5 incorporates or is engaged by abellows 11 which is internally pressurized to urge the seal 5 axiallytowards the matrix 1 and the latter axially against the seal 6. Thebellows 11 is connected by a pipe 12 to spool valve 13 which is movableeither to admit compressed air tapped from the region 9 through a duct14 or to exhaust compressed air from the bellows 11 and the pipe 12through an exhaust duct 15;

The portion of the interior of the housing 3 surrounding the outerperiphery of the seals 5 and 6 and the matrix 1 and containing thebellows 11 receives compressed air that has leaked between the seals andthe end faces of the matrix as indicated by arrows 16. The leakage airis led through a pipe 17 having a restricted mouth to a chamber 18containing a piston 19 carrying a cup washer 20 mounted on one end ofthe spool 21 of the spool valve 13. The piston 19 is urged by a spring22 in the direction in which the spool valve will bleed compressed airfrom the interior of the bellows 11 through the pipe 12 and the exhaustduct 15.

The operation of the pressure-actuated spool valve is as follows: whenleakage of compressed air in the direction of arrows 16 increases, forexample, due to wear,

the piston 19 will be moved downwardly as in FIG. I, against the spring22. This will have the effect of admitting compressed air through thespool valve 13 to the bellows 11 to decrease the leakage flow. If thesealing load should become too great. i.e., the leakage flow decreases.the spring 22 will move the piston 19 upwardly. with respect to FIG. 1,thereby moving the spool 21 to a position in which air in the bellows llwill be exhausted through the spool valve I3 to the exhaust duct 15. Inthis way the leakage flow of compressed air as indicated by arrows 16can be kept substantially con stant, thereby maintaining the sealloading substantially constant and thus minimizing wear of the seals andthe matrix end faces.

Instead of the pressure-actuated spool valve 13 shown in FIG. 1, thepipe 17 can be connected to a fluidic switching device such as thatshown in FIG. 3. In the switching device 25 shown diagrammatically inFIG. 3, the pipe 12 is normally in registration through the device 25with the exhaust duct 15 but when the pressure in the pipe 17 ie. theleakage pressure, increases. the fluid flow from the pipe 14 isdeflected to admit compressed air flowing through the duct 14 to flowthrough the pipe 12 to the bellows 11.

Instead of the pressure-actuated spool valve 13 or fluidic switchingdevice 25, the pressure in the pipe 17 may be used to operate a pressuretransducer and this may in turn actuate an electrical switch foreffecting operation of an electric motor or a solenoid arranged to movea fluid control valve for admitting compressed air from the duct 14 tobe admitted to the pipe 12 or compressed air in the pipe I2 to beexhausted through the duct 15.

What I claim as my invention and desire to secure by Letters Patent ofthe United States is:

I. A rotary regenerative heat exchanger comprising a rotatable disc-likematrix having heat exchange passages therein extending between end facesof the ma trix, and seals co-operable with said end faces and deliningareas thereof through which the fluids between which heat exchange is tobe effected will flow in separated streams, at least one of said sealsbeing in the form of a closed loop and having a hollow bellows-likecross-section and inlet means communicating with the interior of saidhollow seal for the admission thereto of a pressurising fluid, the headexchanger also including means for detecting the rate of flow of leakageof heat exchange fluid between one of said seals and the adjacent endface of the matrix, a fluid-responsive device to control the supply ofpressurising fluid to said pressurised seal in response to the detectedrate of leakage flow and duct means provided adjacent said one seal tolead said leakage flow of fluid to said fluid-responsive device.

2. A heat exchanger as claimed in claim 1 in which said fluid-responsivedevice comprises a pressureactuated spool valve connected to controlapplication of pressurising fluid to said pressurised seal.

3. A heat exchanger as claimed in claim 2 in which said spool valveincludes an operating piston responsive to the pressure of said leakagefluid.

4. A heat exchanger as claimed in claim 1 in which said fluid-responsivedevice is a fluidics switching device controlled by said leakage fluidand connected to apply said pressurising fluid to said pressurised seal.

1. A rotary regenerative heat exchanger comprising a rotatable disc-likematrix having heat exchange passages therein extending between end facesof the matrix, and seals co-operable with said end faces and definingareas thereof through which the fluids between which heat exchange is tobe effected will flow in separated streams, at least one of said sealsbeing in the form of a closed loop and having a hollow bellows-likecross-section and inlet means communicating with the interior of saidhollow seal for the admission thereto of a pressurising fluid, the headexchanger also including means for detecting the rate of flow of leakageof heat exchange fluid between one of said seals and the adjacent endface of the matrix, a fluid-responsive device to control the supply ofpressurising fluid to said pressurised seal in response to the detectedrate of leakage flow and duct means provided adjacent said one seal tolead said leakage flow of fluid to said fluid-responsive device.
 2. Aheat exchanger as claimed in claim 1 in which said fluid-responsivedevice comprises a pressure-actuated spool valve connected to controlapplication of pressurising fluid to said pressurised seal.
 3. A heatexchanger as claimed in claim 2 in which said spool valve includes anoperating piston responsive to the pressure of said leakage fluid.
 4. Aheat exchanger as claimed in claim 1 in which said fluid-responsivedevice is a fluidics switching device controlled by said leakage fluidand connected to apply said pressurising fluid to said pressurised seal.